Indexing mechanism



Feb. 3, 1959 A. A. ABRAMosKA Erm.

INDEXING MECHANISM 2 Sheets-Sheet 1 Original Filed Sept. 28, 1951 A. A. ABRAMosKA ET AL 2,871,721

Feb. 3, 1959 INDEXING MECHANISM 2 Sheets-Sheet 2 Original Filed Sept. 28, 1951 a M R4 my MA Y0 .5M W mRx lum A. R. .D EN M W United States Patent() 2,871,721 LNDEXING MECHANISM Alfred A. Abramoska and John R. Cox, Cleveland,..0hio, assignors to The Balas `Collet Manufacturing Company, a corporation of Ohio Original application September 28, 1951, Serial No. 248,712, now Patent No. 2,704,671, dated March 22, 1955. Divided and lthis application May 11, 1954, Serial No. 428,970

Claims. ('Cl. 7 4-535) Our invention relates to indexing mechanisms for rotatable members, such as for example, chucks for holding tools, workpieces and the like.

This application is a division of our oo-pending application Serial No. 248,712, now Patent No. 2,704,671, led September 28, 1951.

An object of our invention is to provide an improved indexing mechanism for eiiicient and facile operation of a rotatable member, such as a chuck.

Another object is the provision of an improved mechanism and construction in a rotatable head.

Another object is the provision for improved indexing means for holding a rotatable head or member in a preselected rotative position.

Another object is the provision of a mechanism having an indexing member for selectively engaging a rotatable head or member in a desired position.

Another object is the provision of a chuck or other roi tatable member having an improved indexing device and having a plurality of cooperative indexing means for holding the chuck or other member in a selected one of a plurality of arrangements.

Another object is the provision of an indexing device for a rotatable chuck or other rotatable member having a plurality of indexing plungers and a plurality of setsy of recesses in the rotatable head or member, each set cooperating with a different plunger. l

Another object is the provision of a construction of indexing mechanism provided for maximum liexibility and selection lof rotative positions of a rotatablemember', such as a chuck.

Still another object is the provision for an arrangement and combination of features to provide results and to operate in a manner not heretofore known.

Other objects and a fuller understanding of our invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawings, in which:

Figure l is a plan view of our device;

Figure 2 is a cross-sectional view of our device taken through the line 2-2 of Figure l;

Figure 3 is a partial cross-sectional view of our device taken through the line 3 3 of Figure l;` l

Figure 4 is a horizontal cross-sectional view of our device taken through the line 4-4 of Figure 2;

Figure 5 is a horizontal sectional view of our device taken through the line 5--5 of Figure 2; and

Figure 6 is a partial sectional view of our device taken through the line 6 6- of Figure 1. v

In the several views of the drawing, the base member or mounting plate is represented by the reference character 11. The base member 11 is provided with ears 12, which are for mounting the base member 11 to the machine or apparatus tol which our chuck is'mounted in use. A generally cylindrical-shaped body member 14 is axially aligned with the base member 11 and mounted thereto by a ring cap 15; The ring cap 15 is arranged to hold the 2,871,721 Patented Feb. 3, 195e 'body member 14 to the base member 11 and at the same time to permit rotation of the body member 14 relative to the base member 11. The body member 14 has a bottom plate 13 secured thereto to become a part of, and to move with, the body member 14.

A plurality of screw bolts 51 extending upwardly from the base member 11 hold the ring cap 15 in position on the base member 11. The ring cap 15 overlaps the outer edge of the bottom plate 13 to hold the assembled body member 14 and bottom plate 13 to the base member 11,

while'permitting rotation of the assembled body member l 14 with the bottomplate 13 relative to the base member 11.

The cylindrical body member 14 has three enlargements or bosses 14- extending longitudinally thereof at three spaced intervals. Also the body member 14 has a flange portion 14-b extending around its peripheral edge. At its lower portiomthe flange 14-b overlaps to a small degree the upper ilange of the ring cap 15.

The body member 14 has a central bore extending down from its upper end and within this bore there is positioned a contractible resilient collet 22. The collet is split, as shown, to have a plurality of jaws resiliently movable realtive to each otherr and adapted to grip a tool orv workpiece held between the jaws when contracted inwardly. An actuating sleeve 21 positioned within the bore of body member 14 surrounds the collet 22. The cammed surfaces of collet 22 and actuating sleeve 21 are suclthat upon their engagement and the movement kof the actuating sleeve 21, the collet is contracted andreleased in accordance with the direction of movement of the actuating sleeve 21. Upon upward movement of the actuating sleeve 21, the collet jaws are llexed to contract the collet 22 and to grip the tool or workpiece positioned in theV collet. Upon downward movement of the actuating sleeve 21, the collet is released by the actuating sleeve and the jaws resume their straight and uncontracted position.

Directly below the bore containing the collet and actuating sleeveI there is an open space 16 separated by a wall from the described bore. Within the open space 16 there is mounted a flexible and resilient diaphragm 17 made of rubber-like material or other suitable resilient material appropriate for the flexing of the diaphragm 17. The diaphragm is clamped by the body member 14 and the bottom plate 13 around its peripheral edges by a plurality of screw bolts 53. The screw bolts 5'3 extend downwardly ofthe llange 14-b of the body member through the rubber diaphragm and into the bottom plate 13.

A steel plate 18 rests upon the top of the diaphragm 17 and almost covers the exposed portion of the diaphragm, extending across the area of the open space 16. The' steel plate 13 is relatively rigid and is arranged to move up and down as the exible diaphragm 17, upon being flexed, moves up and down in the open space 16. There isv suliicient space above the steel plate 18 tov permit the required amount of movement of the steel plate las the diaphragm 17 may ilex upwardly.

The open space 16 includes a chamber in its lower portion below the rubber diaphragm 17. Upon the introduction of compressedA air into the chamber, of which the diaphragm 17 forms a walls, the compressed air tends to flex or force the diaphragm upwardly and thus to raise the steel plate 18 carried upon the rubber diaphragm. Thus, there is an air chamber within the rotatable body member or head of the chuck, the chamber having a flexible wall which changes position in accordance with the introduction of uid into the chamber, the iluid being introduced differing in pressure from atmospheric pressure and higher than atmospheric pressure.

Three handles 26 are mounted in the bosses or enlargements 14-a in a manner such that the three handles 26 extend horizontally outward from the body member. These handles facilitate manual turning of the rotatable head of the chuck as desired. A vent 20 extends from the upper portion of the open space 16 above the diaphragm. The vent 20 communicates with a hollow opening in one of the handles 26 and thus provides a vent or communication between the top portion of the open space above the diaphragm with atmosphere. Upon the raising of the diaphragm by compressed air ybelow the diaphragm, the air above the diaphragm may readily escape into atmosphere without being compressed itself.

Three reciprocating pins 19 are mounted in suitable openings'in the body member 14 below the actuating7 sleeve 21. The bottom ends of the pins 19 rest upon the steel plate 18 and the upper ends of the pins 19 engage the bottom of the actuating sleeve 21. As the pins 19 are free to reciprocate in the body member 14, the raising of the steel plate 13 by the diaphragm 17 pushes the pins 19 upwardly, which in turn push the actuating sleeve 21 upwardly to contract the collet 22. Therefore, fluid under pressure other than atmospheric pressure, such as compressed air, introduced under the rubber diaphragm within the enclosed chamber in the body member, causes the collet to contract and to grip the tool or workpiece positioned therein.

Radially disposed in the body member 14 at the location of the bosses or enlargements 14-a are three bores for accommodating detent balls 23. Each of the three detent balls 23 is resiliently held inwardly by a spring 24, which in turn is retained in position by a retainer plug 25 threadably engaged in a `boss or enlargement 1li-a. A recess or groove 52 is formed in the outer portion of the actuating sleeve 21 and this groove 52 has inclined walls, as shown in Figure 2. The arrangement of the detent balls 23 and the inclined walls of the groove or recess 52 is such that the balls 23 resiliently urge the actuating sleeve 21 downwardly upon the lowering of the diaphragm 17 when compressed air is released from the air chamber, The arrangement of the detent balls 23 and the walls of the recess 52 also is such that the actuating sleeve is resiliently retained in the body, even though the collet 22 may be temporarily removed. The cooperating of the co-acting cammed surfaces of the collet and actuating sleeve and the action of the detent balls upon the walls of the groove 52 are such that when.

the force of the compressed uid is removed from the chamber and the diaphragm is lowered, the actuating sleeve 21 is moved downwardly and the collet is released. to its normal uncontracted position. Upward movement of the actuating sleeve by the compressed fluid moving the diaphragm upwardly tends to overcome the springs 24 to permit the actuating sleeve 21 to contract the collet 22.

Axially within the body member 14 at the lower portion of the bore there is a tapped hole 28 and a workstop 27 threadably secured to the base member by means. of a threaded stem in the tapped hole 2S. The workstop 27 of a selected height adjusts the amount that a tool or workpiece may move down in the bore within the collet. Suitably arranged chip clearance holes 29 and 30 are disposedv in the body member 14, as shown in the drawings, particularly in Figure 2. These permit chips to escape out from below the collet and below the actuating sleeve.

In practice, we prefer to utilize compressed air for actuating our device. However, other uid under a pressure different from atmospheric pressure could be utilized. For the purpose of this description, we will generally refer to compressed air as the fluid being utilized. A pipe 32 threadably engaged to the base member 11 is adapted to communicate with a source of compressed air, such as a tank or compressor. Formed lwithin the base member 11 there is a conduit or i101@ 33 extending radially from the center of the -base member to communicate with the pipe 32. Axially positioned within the base member 11 there is an open space at the end of the conduit 33. Formed within the bottom plate 13 of the rotatable head there is another enlarged space which registers with the central enlarged space of the base member 11. Positioned within the mating enlarged spaces in Imembers 11 and 13 there is a bronze bushing 34.v This'bushing 34 is partially within the central open space in the member 11 and partially within the open space within the member 13, and thus extends between the two. There is a slight clearance between members 11 and 13 in the local Vicinity of the bushing 34. The arrangement of the bushing 34 and the registering central open spaces in members 11 and 13 is such that the bushing 34 forms a male member extending from one mem-v ber into the open space of the other member.

To provide a hermetic seal between the bushing 34 and the base member 11, an O-ring 36 of rubber or other suitable sealing material is positioned in a groove in the bushing 34 and in sealing engagement with the base member 11. Another O-ring 37 or other seal is provided between the upper portion of the bushing 34 and the plate 13 to provide a hermetic seal between the bushing and rotatable head. An opening 35 extends axially through the bushing 34 and is in communication with the conduit 33 in the base member. An open space 38 above the bushing 34 provides communication through the member 13 to the chamber within the body member below the diaphragm 17. Thus, compressed air flowing through the pipe 32 flows through the conduit 33 up through the hole 35 in the bushing 34, through the vertical hole 38 and into the chamber in the lower portion of the open space 16 below the diaphragm-17. This compressed air flowing into the chuck from the pipe 32 forces the rubber .diaphragm upward to actuate the actuating sleeve and to contract the collet.

As the bushing 34 is sealed to both the non-rotating member 11 and the rotating member 13, there is a slippage between the bushing and its O-ring seals relative to one orrnore of members 11 and 13. The bushing 34 may -be so tightly engaged through the O-ring 37 to the member 13 thatV the bushing 34 will rotate as the head of the chuck rotates and thus there will be slippage between the lower end of the bushing 34 and the lower O-ring 36 relative to the base member 11. Conversely, the bushing 34 may more tightly engage the base member 11 and thus there will be slippage ybetween the bushing and the upper O-ring 37 relative to the member 13. Also, the relatively' tight engagement may be substantially the same at both the upper and lower portions of the bushing 34 and thus there may be some relative movement or slippage between the bushing 34 and both the members 11 and 13. In any event, the bushing 34 provides u a pin or axle upon which the rotating part pivots or turns or is turned. The bushing 34 may be referred to as a pivot pin or axle for the rotating head of the chuck whether it turns with,l or is stationary relative to, the rotating part.

By the arrangement described, it is to be noted that upon introduction of compressed air to actuate the chuck, there is no binding between the rotating part and the stationary part of the chuck because the air chamber and diaphragm are both within the rotating head. The bushing provides both a pivot pin and a means of introducing compressed air into the air chamber. The moving parts for contracting the collet are all within the rotating head. The base member introduces the compressed air through the central opening in the bushing to the chamber within the rotating head or body of the chuck.

Extending out from one side of, and integral with, the ring cap 15 is the extension or arm portion 15-a. The extension 15-a provides the housing and support for the indexing arrangement utilized in our device. Two openings extend through the arm portion 15-a of the ring cap and are disposed in a radial-direction toward the axial center of the rotatable head. Mounted in one of the radially directed openings in the arm 15-a is an indexing plunger 40 adapted to reciprocate in a sleeve bushing 42 within the radial opening. The plunger 40 has a free sliding tit in the bushing 4Z and is adapted to move radially inward and outward vrelative to the bottom plate 13 of the rotatable body. The inner end, that is the end directed toward the bottom plate 13, is rounded to form the round end 40-a. Formed in the outer peripheral wall of the bottom plate 13 of the rotatable head are six round openings 4S adapted to complementarily tit and receive the round end 40-a of the plunger 4G. When the plunger 40 is in its inward position, the round end 40-a nts within one of the six round openings 48 and thus locks the rotatable head against rotation. A coil spring 46 at the outer end of the plunger .46 is arranged to resiliently urge the plunger 40 radially inward toward the bottom plate 13 and thus into one of the round openings 48. A retaining plug 47 threadably screwed into the arm portion 15-:1 retains the spring 46 in position to resiliently press against the plunger 40 and also provides for adjustment of the spring tension to be applied.

Formed in the plunger 40 in its upper wall and near its rear or outer end is a notch'40-c, this upper notch 40-c extending crosswise of the axis of the' plunger. Formed in the lower portion of the plunger 40 below the upper notch 4tl-c is a lower notch or cutaway portion 40-b. As shown in the drawings, the upper notch 40-c has a semi-cylindrical wall, whereas the lower notch 40-b extends lengthwise of the plunger 40 a greater distance, as particularly seen in Figure 3.

Also extending in a radial direction relative to the rotatable head and disposed within the arm or extension IS-a is another plunger 41. Plunger 41 also slidably rides in a sleeve bushing 42 within the opening extending through the arm 15-a. The plunger 41 is similarly resiliently urged radially inward toward the rotatable head of the chuck by a coil spring 46 retained by the retaining plug 47. As in the case of the other plunger, turning the plug 47 will adjust the tension of the spring 46.

The plunger 41 has an end 41-:1 which in cross-section has a rectangular shape and which in plan View has a wedge shape, as seen particularly in Figure 4. Formed in the outer peripheral wall of the bottom plate 13 of the rotatable head there are four sockets or openings 49, these sockets or openings having a rectangular cross-section with sloping walls to complement the shape of the wedge-shaped end 41-tz of the plunger 41. The rectangular or wedge-shaped end 41-11 is adapted to enter andl be complementarily received in each of the rectangularshaped openings 49. The difference in the shapes of the round end 40-11 and the rectangular end 4141 relative to the sockets 48 and 49 is such that the rectangular wedge-shaped end 41a will t only in the rectangularshaped sockets 49. Thus, the plunger 40 cooperates only with the six sockets 48 and the plunger 41 cooperates only with the four sockets 49.

The plunger 41 has an upper notch 41-c extending across its upper portion near its rear or outer end. The plunger 41 also has a lower notch 41-b extending across its lower portion near its outer end and below the upper notch 41-c. The upper notch 41-c of the plunger 41 corresponds in size and position with the upper notch 4il-c of the plunger 40. Likewise, the lower notch 41-b of the plunger 41 corresponds in size and position with the lower notch 40-b of the plunger 40.

Disposed in a bore extending transversely of the arm or extension portion 1S-a is an actuating member 43. The actuating member 43 is adapted to slidably rotate within the bore in the arm IS-a receiving the member. Extending longitudinally of the cylindrical-shaped actuating member 43 there is a cutaway portion or cross-slot 43-rz. The cutaway portion 43-a shown in Figures 2,

3 and 6, has a tlat wall and a short wall, the short wall being disposed substantially radial of the actuating member 43. The short wall of the cutaway portion 43-a is adapted to complementarily engage the rear wall of the lower notch 40b of the plunger 40 and the lower notch 41-b of the plunger 41. A handle 44 extending from the outward end of the actuating member 43 is adapted to rotate the actuating member 43. Downward movement of the handle 44 rotates the actuating member 43 in a counter-clockwise direction, as seen in Figures 2 and 3. A spring 45l suitably anchored between the handle 44 and the arm portion 15-a and coiled around the outwardly extending portion of the actuating member 43 is biased to maintain the handle 44 in the upward position of Figure 2 and to rotate the actuating member 43 in a clockwise direction, as seen in Figures 2 and 3. A cross-pin 39 disposed transversely of the extension or arm 15a engages in a groove provided in the actuating member 43 for the purpose of retaining the actuating member 43 in position and at the same time to permit rotation of the actuating member 43. For removal of the actuating member 43, the cross-pin 39 is removed and the actuating member is longitudinally pulled out of the arm or extension 15-a.

A selection pin or bolt is disposed transversely of the arm or extension 15-a and above the actuating member 43. The pin 5t) has a sliding fit with the bore -provided for it in the arm 15-a so that the pin S0 may readily be slid longitudinally of its length and its position relative to the arm 15-[1 modified. The pin 50 is somewhat longer than the width of the arm or extension 15-a so that one end or the other of the pin 50 protrudes. By manually pressing on the protruding end to press it inwardly of the arm ElS-a, the longitudinal position of the pin is changed. There aretwo annular grooves provided in the pin 5t), the annular groove 5tl-a being near one end of the pin and the annular groove 50-b being near the other end. The relative positions of the annular grooves Sil-a and Sil-b is illustrated in Figure 6. When the pin 50 is moved to one of its positions, such as in Figure 6, then the annular groove Sit-b clears the plunger 41 and permits the plunger '41 to reciprocate without interference of the pin 50. When in this same position of Figure, the intermediate portion of pin 50, having its maximum diameter, is positioned within the upper notch 40-0 of the plunger 40 and thus retains the plunger 40 in its rearward or withdrawn position, as shown in Figure 3. In Figure 3, the plunger 46 is withdrawn away from the lower plate 13 and thus out of a round socket 48. The plunger 4t) is held in this retracted position against the resilient pressure of the spring 46 by the interlocking of the pin S0 and the plunger 40, through the interengagement of the pin 50 in the upper notch 40-c. The plunger 40 is initially pulled back to its retracted or withdrawn position by the actuating member 43 upon downward movement of the handle 44. When in this retracted position, the pin 5) is longitudinally slid to the position shown in Figures 3 and 6 so that the pin 50 retains the plunger 40 in its retracted position after the handle 44 is released.

To restrain the plunger 41 in its rearward or retracted position the handle 44 is pressed downwardly to rotate the actuating member 43. This causes the short flat side of the cutaway portion 43-a of the actuating member 43 to engage a side of the lower notch 41-b ofthe plunger 41 and to draw the plunger 41 rearwardly. When in this rearward position, the protruding end of the pin 50 is manually pressed to change the positions of the annular grooves 50-a and 50-b and thus to clear the upper notch Ml-c of the plunger 40 and to cause the pin 50 to interlock with the upper notch 4l-c of the plunger 41. In this position, the plunger 41 is held in retracted position by the pin 50 while the plunger 40 is free to reciprocate. The pin 50 therefore acts as a selective means to determine which of the plungers is to be free to enter the sockets in the Vrotatable head of the chuck, one plunger or the other being held in retracted position by the selection pin 50. The free plunger is resiliently moved inwardly to engage in a complementary socket of the rotatable head and is retracted by operation of the actuating member. The free plunger is adapted to enter only one of the two sets of sockets, plunger 40 cooperating with the sockets 48 and the plunger 41 cooperating with the sockets 49. In the arrangement shown, there are six equidistantly spaced sockets 48 and four equidistantly spaced sockets 49 in the circle of the outer peripheral wall of the rotatable head, and particularly the bottom plate 13 thereof.

Other arrangements of holes or sockets may be formed in the bottom plate 13 so that any desired indexing arrangement may be had. Likewise, more than two plungers may be utilized, if desired, to obtain greater subdivision of the circle and selectivity in choice of positions in which the rotatable head is to be locked. Thus, the rotatable head of the chuck may be rotated and held in a number of selected positions by releasing the plunger then being used and by rotating the head to the next socket corresponding to the plunger being utilized. The construction provides a iiexible arrangement adapted to meet a wide variety of conditionsand operating requirements.

Our construction provides a chuck which is quickly and easily operated by iiuid pressure and at the same time which is readily rotated without binding by the force of the fluid pressure. It also combines an indexing arrangement which is particularly appropriate and convenient for the use of the rotating chuck. The advantages and improved resultsobtainable with our improved chuck will be readily ascertainable by those using such devices and appreciating the shortcomings and disadvantages of the prior devices.

The present disclosure includes the description contained in the appended claims, as well as the above description and drawings.

Although this invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be' resorted to without departing from the spirit and scope of the invention as hereinafter claimed.

What is claimed is:

l. Indexing mechanism comprising in combination a base member, a rotatable member rotatably carried by.

said base member, said rotatable member having a plurality of sets of sockets formed therein, each set of sockets having its respective sockets equidistantly spaced apart around the circumferential extent of said rotatable member and each set including a diiierent number of sockets, a plurality of plungers carried by said base member and reciprocal toward and away from said rotatable member, each of said plungers having an end adapted to fit within the respective sockets of one set only upon movement of said plunger toward said rotatable member, each set of sockets having its respective sockets formed to accommodate an end of one of said plungers only, operating means for moving said plungers relative to said rotatable member, and selective means for withholding from operating all but one of said plungers, said plungers in `cooperation with said sockets 'providing for indexing of said rotatable member.

2. Indexing mechanism comprising in combination a base member, a rotatable member rotatably carried by said base member, said rotatable member having a plurality of sets of plunger-engaging means carried thereby, the respective plunger-engaging means of each set being equidistantly spaced apart and each set including a different number of plunger-engaging means, a plurality of plungers reciprocably carried by said base member and arranged to be moved toward and away from said rotatable member, and operating means for moving a selected one of said plungers relative to said rotatable member,

each of said plungers being'arranged to interengage with the plunger-engaging means of one of said sets only upon movement toward said rotatable member, and each set of plunger-engaging means having its respective plungerengaging means arranged to engage with only one of said plungers to provide for indexing of'said rotatable member by a selected plunger and corresponding set of plungerengaging means.

3. The combination of a rotatable head, a base member rotatably carrying said head, and indexing means for indexing said head in a plurality of selectable cycles, said indexing means including a plurality of reciprocal plungers carried by said base member, a plurality of sets of plunger stops carried by said head', the stops of each set being arranged to interlock with one only of said plungers, the stops of each set being arranged to provide an index- Ving cycle dilerent in number and spacing from the indexing cycle of the stops of the other of said sets, selective means for holding all but a selected one of said plungers .away from said head, and operating means for moving a selected one of said plungers relative to said head.

4. In a chucking device having 'a base member and a rotatable head carried by the base member, an indexing device comprising the combination of a plurality of plung- -ers reciprocal relative to said head, support means carrying said plungers, a plurality of stops carried by said head, said stops being arranged in groups, each group being varranged to co-act with only one of said plungers and the -cyclic arrangement of the receptacles of each group being different than the cyclic arrangement of other receptacles, the lstops of each group being complementary to a respective plunger to provide for interlocking of each plunger with the stops of only one group of stops, selective means for releasing a selected plunger for operation, biasing means for biasing a selected plunger toward the said head to interlock with a stop of a corresponding group, and operatlng means for moving a selected plunger away from said head in opposition to said biasing means to unlock the interlocked plunger and stop and to permit rotation of said head.

5. In a chucking device having a base member and a'rotatable head carried by the base member, the combmation of a iirst plurality of locking elements carried by said head in a iirst Cyclic arrangement, a second plurallty of locking elements carried by said head in a second cyclic arrangement, a first plunger reciprocably carried by said base member to move toward and away from said head, said first plunger having an end portion arranged to interlock only with locking elements of said iirst plurality of elements, a second plunger reciprocably carried by said base member to move toward and away from said head, said second plunger having an end portion arranged. to interlock only with locking elements of said second plurality of elements, and operating means for operating a selected one of said plungers to interlock with elements of a corresponding group of elements.

6. In a chucking device having a base member and arotatable head carried by the base member, the combination of a first plurality of locking elements carried by said head in a first cyclic arrangement, a second plurality of locking elements carried by said head in a seel ond cyclic arrangement, a first plunger reciprocably carried :by said base member to move toward and away from said head, said first plunger having an end portion arranged to interlock only with locking elements of said first plurality of elements, a second plunger reciprocably carried by said base member to move toward and away from said head, said second plunger having an end portion arranged to interlock only with locking elements of said second plurality of elements, resilient means urging said plungers toward said head, a selector for'holding one of said plungers away from said head, and an actuator formoving the other of said plungers in opposition to the resilient means awaysfrom said head to unlock the same from an element for permitting rotation of said head.

7. In a chucking device having a base member and a rotatable head carried by the base member, the combination of a first plurality of locking elements carried by said head in a first cyclic arrangement, a second plurality of locking elements carried by said head in a second cyclic arrangement, a first engaging member movably carried by said base member to move relative to said head, said rst engaging member having a por-'4 tion arranged to interlock only with locking elements of said first plurality of elements, a second engaging member movably carried by said base member to move relative to said head, said second engaging member having a portion arranged to interlock only with locking elements of said second plurality of elements, resilient means urging said engaging members toward said head, a selector for holding a selected one of said engaging members away from said head, and an actuator for moving the other of said engaging members in opposition to the resilient means away from said head to unlock the same from an element for permitting rotation of said head.

8. In a device having a base member and a rotatable member carried by the base member, an indexing device comprising the combination of a plurality of plungers reciprocal relative to said rotatable member, support means carrying said plungers, a plurality of stops carried :by said rotatable member, said stops being arranged in groups, each group being arranged to co-act with only one of said plungers and the cyclic arrangement of the receptacles of each group being different from the cyclic arrangement of other receptacles, the stops of each group being complementary to a respective plunger to provide for interlocking of each plunger with the stops of only one group of stops, selective means for releasing a selected plunger for operation, biasing means for biasing a selected plunger toward the said rotatable member to interlock With a stop of a corresponding group, and operating means for moving a selected plunger away from said rotatable member in opposition to said biasing means to unlock the interlocked plunger and stop and to permit rotation of said rotatable member.

9. In a device having a base member and a rotatable member carried by the base member, the combination of a first plurality of locking elements carried by said head in a first cyclic arrangement, a second plurality of locking elements carried by said rotatable member in a second cyclic arrangement, a first plunger reciprocably carried by said base member to move toward and away from said rotatable member, said first plunger having an end portion arranged to interlock only with locking elements of said first plurality of elements, a second plunger reciprocably carried by said base member to move toward and away from said rotatable member, said second plunger having an end portion arranged to interlock only with locking elements of said second plurality of elements, and operating means for operating a selected one of said plungers to interlock with elements of a corresponding group of elements.

10. In a device having a base member and a rotatable member carried by the base member, the combination of a rst plurality of locking elements carried by said rotatable member in a first cyclic arrangement, a second plurality of locking elements carried by said rotatable member in a second cyclic arrangement, a i'irst plunger reciprocably carried by said base member to move toward and away from said rotatable member, said rst plunger having an end portion arranged to interlock only with locking elements of said first plurality of elements, a second plunger reciprocably carried 'by said base member to move toward and away from said rotatable member, said second plunger having an end portion arranged to interlock only with locking elements of said second plurality of elements, resilientmeans urging said plungers toward said rotatable member, a selector for holding one of said plungers away from said rotatable member, and an actuator l'for moving the other of said plungers in, opposition to the resilient means away from said rotatable member to unlock the same from an element for permitting rotation of said rotatable member.

References Cited in the iile of this patent UNITED STATES PATENTS 38,364 Godwin Apr. 28, 1863 639,892 Fay Dec. 26, 1899 646,287 Hundhausen Mar. 27, 1900 1,912,045 Seagren May 30, 1933 2,030,339 Weightman Feb. 11, 1936 2,476,195 Horman July 12, 1949 2,704,672 Wiltsie et al. Mar. 22, 1955 FOREIGN PATENTS l 3,860 Great Britain Feb. 16, 1907 of 1906 659,311 Great Britain Oct, 24, 1951 

